Earthquake Protection

28 March 2011

For more than 15 years, we've been doing a lot to make sure the city's reservoirs and arterial roads can withstand a significant earthquake.

Construction work continues on the Messines Road reservoirs

Construction work continues on the Messines Road reservoirs

We spend more than $30 million a year renewing and upgrading the city's infrastructure, and making the city more resilient to earthquakes is a big part of that.

The Council's Infrastructure Director, Stavros Michael, says since the mid-1990s there has been a particular focus on protecting the water we store in the city and key access routes.

In the case of roads, this has involved building new retaining walls and support structures and stabilising and strengthening slopes that could potentially come down. For instance, more than
$5 million has been spent progressively strengthening Ngaio Gorge Road since 2000. The road would be an essential access route in and out of the city if the Ngauranga Gorge was blocked.

We have also looked at our tunnels and work will start later this year to secure the bank above the entrance on the city-side of the Karori tunnel. We're planning to strengthen the concrete entrance portal next year.

To protect our water we have been progressively replacing old reservoirs with stronger and larger models, installing automatic shut-off valves on new and existing reservoirs and making sure all the new water and sewage pipes we put in are earthquake-resistant.

"It's an expensive and long-term process but 90 percent of our stored water is now in reservoirs that have automatic, seismic-sensitive shut-off valves," says Stavros. "We may not be able to access the water supplies straight away after an earthquake and it probably won't be coming out of your tap - which is why we continually remind Wellingtonians to store emergency water and supplies of their own. But unless there is a catastrophic event, our work does mean we should have reasonable supplies of water in the city that we will be able to draw on and distribute to the community."

We have 58 large reservoirs including 11 built since 2000. The new ones include reservoirs in Miramar, Mount Albert, Kelburn, Grenada North, Roseneath, Wadestown, Lincolnshire and Khandallah.

A new $6 million reservoir under construction in Messines Road in Karori is nearly twice the size of the 1925 and 1935 reservoirs it is replacing and has been designed to meet modern standards for earthquake resilience.

Planning is also under way for another major reservoir to service the central business district that will eventually replace the 1911 reservoir in Bell Road, Mount Cook. This will be a lot larger and include additional capacity specifically for Wellington Hospital to use in emergencies.

Stavros says all structures that house our sewage and water pumps have been inspected in recent years and the equipment in them is tied down and strapped back. We also consider what will happen - where the waste will end up - if these systems fail.

"There is still a lot more to be done, and it will take many years before all our old pipes are replaced, but plans are in place to progressively make the city's infrastructure more resilient to earthquakes," he says.

"Part of that has involved working with a wide range of organisations and service providers through the Wellington Lifelines Group to identify vulnerable areas, address shortcomings and collectively plan how we will work together to restore essential services."